Specific Process Knowledge/Characterization/Dektak XTA: Difference between revisions
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There is also a tiny contribution to the total error from the instrument's limited resolution and finally of course there is random noise in any measurement. For many repeated measurements of the same line on the standard step height (a rigid, well defined vertical step) we have found the random error from the DektakXT is on the order of ± 5 nm for the 917 nm standard and 0.05 µm for the 24.925 µm standard. The random error with the P17 profiler is even smaller. | There is also a tiny contribution to the total error from the instrument's limited resolution and finally of course there is random noise in any measurement. For many repeated measurements of the same line on the standard step height (a rigid, well defined vertical step) we have found the random error from the DektakXT is on the order of ± 5 nm for the 917 nm standard and 0.05 µm for the 24.925 µm standard. The random error with the P17 profiler is even smaller. | ||
To estimate the overall accuracy of the profiler's measurements you can convolute these various sources of error. The error sources are shown graphically in Figure 2 for measuring the small standard step with the DektakXT's smallest range. You can see an uncertainty budget for the DektakXT measurements here (made by Rebecca Ettlinger): [[Media: | To estimate the overall accuracy of the profiler's measurements you can convolute these various sources of error. The error sources are shown graphically in Figure 2 for measuring the small standard step with the DektakXT's smallest range. You can see an uncertainty budget for the DektakXT measurements here (''made by Rebecca Ettlinger''): [[Media:Uncertainty budget Dektak rev.xlsx |Uncertainty budget Dektak rev.xlsx]]. It is based on the assumption that all the error sources are independent and can therefore be added by the sum of squares method. | ||
The resulting error calculation for the DektakXT of a 1 µm very well defined standard step is about 2 % (as the uncertainty on the calibration standard dominates), while for a very well defined step of 25 µm the cumulative error is about 0.7-1 %. These are the uncertainties listed in [[Specific_Process_Knowledge/Characterization/Profiler|the technical specifications]] for the instruments. However, in real devices the random error will often be much larger than for our standard samples and so the real confidence interval will be larger. | The resulting error calculation for the DektakXT of a 1 µm very well defined standard step is about 2 % (as the uncertainty on the calibration standard dominates), while for a very well defined step of 25 µm the cumulative error is about 0.7-1 %. These are the uncertainties listed in [[Specific_Process_Knowledge/Characterization/Profiler|the technical specifications]] for the instruments. However, in real devices the random error will often be much larger than for our standard samples and so the real confidence interval will be larger. | ||